假设以整数序列1,2,3,…,n作为栈S的输入，利用Pop（出栈）和Push（入栈）操作，编写算法以输出所有可能的输出序列-Assuming a sequence of integers 1,2,3, ..., n as the input stack S, the use of Pop (stack) and Push (stack) operation, write algorithm to output all possible output sequences